A manual work station is a station at which an operator performs a manual task such as attaching one part to another or simply moving an object from one position to another. Operators working at such manual work stations often use tools such as electric moment of force wrenches and screw drivers. Some of these tools are heavy to operate and operators of such tools are often subject to fatigue and stress injuries.
One solution to this problem is to use a balanced lifting device comprising a manipulator arm. The tool is attached to an outermost end of the manipulator arm, which consists of a plurality of pivotally connected arm segments. The pivotally connected arm segments allow the operator to move the tool within a work space. A balancing device is acting on the manipulator arm to compensate for the gravitational force acting on the manipulator arm. This arrangement reduces the effort required to move and use the tool.
A lifting device for use at a work station and provided with a balancing device is revealed in CN 201511364U. This document describes a pneumatic balance assisted manipulator for lifting and positioning a car seat. The balance assisted manipulator is provided with a pneumatic control system mounted on a rotary vertical post. A manipulator arm comprising a plurality of pivotally connected arm segments and cooperating with the pneumatic control system is also mounted on the post. The pneumatic control system balances the force generated by the compressed air and the gravitational force acting on the car seat.
This lifting device is inefficient, has a complex design and occupies a large part of the work space.